Process of making pentamethine cyanine dyes



Patented Oct. 4, 1938 UNITED STATES PATENT OFFICE PROCESS OF CYANIWalter Zch, Dessau in or to'Agfa Ansco N Drawing.

6 Claims. My present invention relates-to dyes of the polymethineseries.

One of its objects is to provide a process of producing dyes from thepolymethine series. Another object are the dyes of the polymethineseries which have proved to be valuable sensitizers. Further objectswill be seen from the detailed specification following hereafter.

The symmetrical pentamethinecyanines have already been proposed assensitizers for the range of wave lengths between 650 and 1000 Accordingto'this invention I have found, that the unsymmetricalpentamethinecyanines are well suited for sensitizing a silver halideemulsion for this range of wave lengths. The progress involved by thenew sensitizers resides not only in the fact that an extraordinary greatnumber of suitable dyes is now available, but also in the fact, that bysuitably combining different quaternary ammonium salts of heterocyclicnitrogenous bases containing a methyl group capable of reaction nearly.any desired maximum of sensitization may be obtained in the infra-redportion of the spectrum. Thus it is possible to adjust the sensitivityof the emulsion according to requirement.

For the preparation of the unsymmetrical pentamethinecyanines there isfirst made an intermediate product by condensing in the presence of analkaline condensing agent equivalent portions of a quaternary ammoniumsalt of a heterocyclic base containing a methyl group capable ofreaction and of a propene compound of the gen eral formula:

where R stands for alkyl or hydrogen, R for aryl and X for an acidradical.

As alkaline condensing agent I have found suitable, for instance,primary, secondary and tertiary amines, such as methylamine,diethylamine, trimethylamine, triethylamine, piperidine, pyridine, orsodium ethylate, or ethanolamines. The amount of condensing agent usedis preferably a quantity at most equivalent to that of the base which isused, because an increasing amount ,of condensing agent promotes theformation of symmetrical dye from which the intermediate product must beseparated, usually by physical means (crystallization, decocting). Themost suitable amount to be used of each condensing agent can easily bedetermined by experiment. Condensing agents which may casually beapplied Corporation, N. Y., a corporation of New York Application May28, 1934, Serial In Germany June 3, 1933 in excess so DYE Anhalt,Germany, assign- Binghamton,

that nevertheless the formation of intermediate product occurs are theamines. In case of using pyridine or condensing agents of similar actionwhich simultaneously are used as solvents, there may be used an excessfor obvious reasons. advisable to use an amount of the propene compoundsubstantially exceeding the quantity equivalent to that of the base;preferably there is used a more than 10 per cent excess in order toavoid as far as possible the undesired formation of symmetrical dye.

If as heterocyclic base there is used, for example, benzthiazole, thereaction of the 2-methylbenzthiazole alkyl iodide withoz-IlhBIlYlEtll'lidO-yphenylimidopropene hydrochloride in the presenceof piperidine to form a tetramethine dye probably proceeds according tothe following schemez For the production of the pentamethinecyanine dye,the tetramethine dye formed as intermediate product is caused to reactin the presence of an alkaline condensing agent with a quaternaryammonium salt of another heterocyclic base con- It is taining a reactivemethyl group. The reaction probably proceeds according to the followingscheme:

For the condensation with the propene compound and with the tetramethinedye there are suitable all het'erocyclic bases which contain areactivemethyl group, for example, mono-.- and poly-nuclearZ-methylthiazoles, 2-methyl-selenazoles, and 2- or 4-methyl-quinolines.As alkaline condensing agents there may be mentioned, for example,pyridine, piperidine, ethanolamine, alkyl-amines and sodium ethylate.

By use of suitable of heterocyclic bases, there are obtained inaccordance with the invention pentamethinecyanine dyes of the generalformula:

R6 X 7 a R In this formula nsubstituted or substituted phenylene,naphthylene or other polynuclear arylenegroups;

suitable substituents are alkyl, aryl, alkoxy, carbethoxy, thioalkyl,seleno-alkyl, substituted and unsubstituted amino-groups.

A necessary condition is that either Y and Z or R R. and R R shalldiffer from one another.

R and R =alkyl,

X=an inorganic or organic acid radical, for example Cl, Br, I, C104,CH3--CsH4-SO3, CH3SO4, C2H5SO4.

The quinoline nucleuswhich results in case of Y being --CH=CH- may belinked to the polymethenyl chain in 2 or 4 position. Individual hydrogenatoms of the pentamethine chain can be replaced by alkyl groups, forexample by methyl or ethyl.

In the general formula Y and Z may represent sulfur, selenium or thevinyl group CH==CI-I. In

the case of dyes in which, for instance, a thiazole nucleus and aselenazolev nucleus are linked together by a pentamethenyl chain R R Rand R may represent hydrogen, or they may represent alkyl or aryl orcarbethoxy.

m-oom It 1i Rz-G- -C-R4 may represent phenylene, or naphthylene or apolynuclear arylene group, for instance, the corresponding radical ofanthracene, chrysene, fiuorene or acetnaphthene. In the case of Y beingsulfur, Z being selenium,

Ri'C- C-Ra H and Rz-C- -C-R4 being phenylene, the dye is abenzthiazole-benzselenazole-pentamethinecyanine. If Y is selenium, Z issulfur,

is phenylene, and R3 and R4 are hydrogen the dye is abenzselenazole-thiazolepentamethinecyanine. This not only illustratesthe dyes which are contemplated by nomenclature. In the case of Y beingCH CH, Z being sulfur and R R R R being hydrogen,

there result dyes in which a pyridine nucleus is linkedtogether with athiazole nucleus by a groups.

the invention but also the is phenylene, R and R are hydrogen, thereresults a dye in which a quinoline nucleus is linked together with athiazole nucleus by a pentamethenyl chain and is called aquinoline-thiazolepentamethinecyanine. The quinoline nucleus maybelinked in 2 or 4 position. The benzene rings or polynuclear rings fusedon the heterocyclic rings containing a nitrogen atom may be substitutedfor instance by alkyl, alkoxy,

aryl, halogen, substituted or unsubstituted amino The radicals R and Rlinked to the nitrogen atoms of the heterocyclic rings linked togetherby the pentamethenyl chain represent alkyl. X represents an anion, forinstance those disclosed above.

The dyes are obtainable according to the desired solubility in form ofthe bromide, iodide, perchlorate etc. and are used in a quantity such asis usual for the known sensitizing dyes. This quantity may amount toabout 0.5 to 2 milligrams per 1 kg. of emulsion ready for being castwhich contains about 9 per cent of gelatin, 4.5 per cent of silverhalide and the rest water. However, I do not wish to limit my inventionto the quantities just indicated, the most suitable amount will in eachcase be found by a few comparative experiments. The dyes may be added tothe emulsion in form of solutions. Suitable solvents are the alcohols,for instance, methyl or ethyl alcohol which may be used anhydrous ordiluted with water. The dyes are applied to the emulsion during anystage of its production, however, they are preferably added to thefinished emulsion before casting.

The dyes maylikewise be added to the emulsion by bathing the finishedphotographic material in a bath in which the dye is dissolved. Such atreatment may be as follows: The photographic material to be sensitizedis bathed in a solution containing 1 milligram of[3-ethyl-5-methoxybenzselenazole-(Z) [3-ethyl-6-methylquinoline-(2)lrpentamethinecyanine iodide in 500 to 1000 cc. of anaqueous solution of methanol of 50 per cent strength for about 5minutes. The material is then dried, whereupon it is ready for use.

The following examples illustrate the invention.

Example 1.-2 grams of 2-methylbenzthiazole ethiodide, 2 grams ofa-phenylamido-v-phenylimidopropene hydrochloride (prepared according toClaisen, Berichte der deutschen ohemischen Gesellschaft, vol. 36, page3667) and 10 cc. of alcohol are heated to boiling, 0.5 cc. of piperidineare added and the whole is boiled for about a further half hour. Oncooling, there separates the tetramethine dye (intermediate product) ofthe following probable constitution:

The dye is recrystallized from alcohol.

In alcoholic solution, the dye has an absorption maximum at 515/.t/L.

1 gram of the intermediate product so obtained, 1 gram of 2:5:5trimethylbenzselenazole ethiodide and cc. of alcohol are heated toboiling and there is then added gradually about 1 cc. of diethylamine,boiling being continued until the reaction mixture has become deep blue.On cooling, IS-ethyhbenzthiazole- (2) l-[3-ethyl-5.6-dimethylbenzselenazo'le- (2)] pentamethinecyanine iodide of the probableformula:

zHs

separates in the form of coarse green crystals.

The alcoholic solution of the dye has an absorption maximum at a wavelength ofabout 670 Incorporated in a silver bromide emulsion containingabout 4 per cent of silver iodide the dye imparts to it a range ofsensitivity from about 600 to 800 with a maximum of about 715 l. Example2.-2 grams of 2-methyl-5:6-dimethoxy-benzthiazole ethiodide and 2 gramsof O6" phenylamido-'y-phenylimido-propene hydrochloride are dissolved in10 cc. of boiling alcohol, then 0.5 cc. of triethanolamine is added andthe whole is maintained boiling for about 30 minutes. From the deep redsolution, the intermediate dye of the probable formula precipitates inthe form of blue-red crystals. From alcohol the dye crystallizes as ared-brown crystalline powder. Its alcoholic solution has an indefiniteabsorption maximum at about 525,114].- The intermediate product has amedium sensitization intensity. Its maximum of sensitization is 560/.L/Land its range of sensitization is about 510 to 600 1 gram of theintermediate product thus obtained and 2 grams of 2:4-dimethylthiazoleethiodide are heated in 10 cc. of alcohol to boiling for about 10minutes with the addition of 1 cc. of diethylamine. On cooling thereseparates from the deep blue reaction liquid[3-ethyl-5.6-dimethoxy-benzthiazole-(2)l [3-ethyl-4-methyl-thiazole- (2)l-pentamethinecyanine methylthio-pentacarbocyanine iodide of theprobable formula The alcoholic solution of the dye has an absorptionmaximum at a Wave length of'about 665,LL,u..

Incorporated in a silver bromide emulsion containing about 2 per cent ofsilver iodide the dye imparts to it a range of sensitivity from aboutGOO/14L to 800 with a maximum of about 705 Example 3.--A mixture of 2grams of 2-methyl- [naphto-2'.1 :4.5-thiazole] ethiodide and 2 grams ofu-phenylamido-'y-phenylimidopropene hydrochloride in 10 cc. of alcoholis heated to boiling for about hour with 0.5 cc. of diethylamine. Oncooling, there, separates from the red-violet deep blue.

reaction mass the'intermediate dye of the probable constitution:

I g s in the form of blackish-brown crystals.

' The alcoholic'solution of the dye has an absorption maximum at 540M,-

1 gram of'the dye obtained and 0.6 gram of Z-methylbenzthiazoleethiodide are dissolved in 10 cc. of hot alcohol and the solution isheated to boiling, whilst 0.5 cc. diethylamine is gradually added, untilthe reaction mixture becomes By the addition of about 5 cc. of asolution of sodium perchlorate of 10 per cent strength,[3-ethyl-{naphto-2.1:4.5-thiazole}- (2)] [3-ethylbenzthiazole-(2)l-'pentamethine cyanine perchlorate of the probable formula:

a mixture of 2 grams of Z-methylbenzselenazole ethiodide and 2 grams ofa-phenylamido-v-phem yl-imidopropene hydrochlorideis first heated forhalf an hour in 10 cc. of alcohol with the addition of 1.5 cc. oftriethanolamine. On cooling the intermediate product of the probable formula:

separates from the violet-red reaction liquid in the form of dark greencrystalline tablets. The alcoholic solution of the product has anindefinite absorption maximum at about 525 The product is a sensitizerfor orange.

Incoporated in a silver bromide emulsion containing about 2 per cent ofsilver iodide the dye imparts to it a range of sensitivity from about510 to 590 with a maximum at about 535 1 gram of the intermediateproduct and 2 grams of 2:4-dimethylthiazo-le ethiodide are dissolved in10 cc. of alcohol and the solution is heated to boiling Whilst about 3cc. of an alcoholic solution of sodium ethylate (containing 3 per centof sodium) are gradually added, until the mass becomes blue. Theunsymmetrical pentamethinecyanine which is precipitated on coolingcrystallizes from alcohol as a blue-black crystalline-powder.

The alcoholic solution of the dye has an absorption maximum at a wavelength of about 660, 4.

Incorporated in a silver bromide emulsion containing about 2 per cent ofsilver iodide the dye imparts to it a range of sensitivity from about570[L}L to 780 with a maximum at about 680 Example 5.--The intermediateproduct of the probable formula:

CzHs I is obtained by using in Example 4 the5-methoxy-2-methyl-benzselenazole ethiodide instead of2-methyl-benzselenazole ethiodide. It crystallizes from alcohol in theform of a dark brown crystalline powder the alcoholic solution of whichhas an absorption maximum at 540 1 gram of the intermediate product soobtained is heated together with 0.6 gram of paratoluquinaldineethiodide in cc.' of alcohol after the addition of 0.4 cc. oftriethanolamine until the reaction mixture becomes dark green. [3-ethyl-5 methoxy-benzselenazole (2)] lethyl 6 methyl-quinoline- (2)l-pentamethinecyanine iodide which separates on cooling and has probablythe formula:

crystallizes from alcohol in small copper-colored deformed tablets.

The alcoholic solution of the dye has an absorption maximum at a wavelength of about 690 Incorporated in a silver bromide emulsion containingabout 2 per cent of silver iodide the dye imparts to it a range ofsensitivity from about GlO/LIL to 810 141. with a maximum at about730/.L/L.

Example 6.2 grams of lepidine methiodide, 2 grams ofu-phenylamido-v-phenylimidopropene hydrochloride, 10 cc. of alcohol and0.5 cc. of tri- -ethanolamine are heated to boiling for about 1 hour. Oncooling, there separates from the redviolet solution the intermediateproduct of the probable formula:

This product is a dye which crystallizes from alcohol in brown-blackcrystalline fragments. Its alcoholic solution has an absorption maximumat about 580mm 1 gram of this intermediate product and 1 gram of2-methylbenzthiazole ethiodide are heated in 5 cc. of alcohol togetherwith about 0.5 cc. of diethylamine until the reaction mass becomes darkgreen. On cooling the [l-methylquinoline(4)] [3-ethyl-benzthiazole-(2)l-pentamethinecyanine iodide separates. The dye has probably theformula:

CzHb

of the probable formula:

CH=OHCH=CHN-C H \/\N/ o 6 H is thus obtained in form of red-browncrystalline little rods.

An alcoholic solution of the product has an indefinite absorptionmaximum at about 535lL/L.

1 gram of the intermediate product is heated in 10 cc. of alcohol with0.8 gram of 2-methylbenzthiazole ethiodide with addition of about 0.5cc. of diethylamine drop by drop, until the reaction mixture becomesblue-green. [1-ethyl-6- methyl-quinoline (2) l [3 ethyl-benzthiazole(2)1-pentamethinecyanine iodide which separates on cooling and hasprobably the formula:

02115 I CgHs crystallizes from alcohol in brown-green deformed crystals.

The alcoholic solution of the dye has an absorption maximum at about 665Incorporated in a silver bromide emulsion containing about 2 per cent ofsilver iodide the dye imparts to it a range of sensitivity from about600 to 800p. with a maximum at about 705 Example 8.2 grams ofZ-methylbenzthiazole ethiodide and 2 grams of a-phenylamido--phenylimido-p-methylpropene hydrochloride (obtainable analogously toa-phenylamido-' -phenylimidopropene hydrochloride from thecorrespondingly substituted propargyl aldehyde-acetal) are dissolved in10 cc. of alcohol, and, after the addition of 0.4 cc. of piperidine, thesolution is heated to boiling for about half an hour. On cooling .1blue.

there separates the intermediate product of the. probable formula:

1 gram of the intermediate product prepared as above described and 1gram of 2-methyl- [naphto-2'.1:4.5-thiazole]-ethiodideare heated at 130C. in 10 cc, of pyridine for about half an hour until the reactionmixture becomes deep On cooling .the unsymmetrical pentamethinecyanineseparates in theform of green crystals. It crystallizes from alcoholinthe form ofgreen rhomboids. l r

The alcoholic solution. of the dye hasan ab-' sorption maximum at about665 Incorporated in a silver. bromide emulsion containing about 4 percent of silver iodide the dye imparts to it a range of sensitivity fromabout 590 to 800 with a maximum at about 710 Example 9.-For preparing[3-ethyl-benzthiazole-(2)]-[1 -methyl quinoline (4) ]-5-methylpentamethinecyanine iodide of L the probable formula 1 gram of theintermediate product described in Example 8 and 1 gram of lepidinemethiodide are heated in cc. of alcohol with the addition of about 1 cc.of diethylamine, until the reaction mixture assumes a permanent greencolor. The

unsymmetrical 'pentamethinecyanine which separates on cooling isfiltered by suction, washed with acetone and recrystallized fromalcohol, whereby it is obtained in the form of a blackbrown crystallinepowder.

Incorporated in a sliver bromide emulsion con taining about 2 per centof silver iodide the dye imparts to it a range of sensitivity from about600,1 1. to 850 with a. maximum at about 770 Example 10.-2 grams of2-methylbenzselenazole ethiodide, 2 grams ofa-phenylamido-yphenylimido-[i-methylpropene hydrochloride, 10

cc. of alcohol and 0.5 cc; of diethylamine are heated in 10 cc. ofalcohol to boiling for about halt an hour. i From the bluish-redreaction mixture the intermediate product ofthe probable formula:

is precipitated by the addition of about 10 cc. of a solution ofpotassium iodide of 5 per cent strength. The dye crystallizes fromalcohol in small red-violet rods. Its alcoholic solution has anindefinite absorption maximum at 530 1 gram of the intermediate productand 1 gram of 2methyl-5:6 ethylenedioxy benzselenazole ethiodide areheated together. in 5 cc. of alcohol, with the addition of, about 1ccuof diethylamine, until the reaction mixture assumes a permanent greencolor. Crystals of the [3-ethyl-benzselenazole- (2)[3-ethyl-5.6-ethylenedioxy-benzselen azole- (2) l-t-methylpentamethinecyanine iodide which is formed and has probably the formula:

are deposited on the walls of the vessel. 'From alcohol, the dyecrystallizes in green rhomboids.

. The alcoholic solution of the dye has an absorption maximum at about685 l.

Incorporated in a silver bromide emulsion containing about 4 per cent ofsilver iodide the dye imparts to it a range of sensitivity from about580 to 830 with a maximum at about 715 Example 11.-For preparing the dye[3-ethyl- 6-ethoxy benzthiazole (2) ]-[3 ethyl-{anthraceno L 2.1':4.5thiazole}- (2) l -pentamethinecy anine iodide corresponding with theformula:

Edam 8 4 grams of Z-methyl-G-ethoxybenzthiazole ethiodide and 4 grams ofu-phenylamido-ymhenylimidopropene hydrochloride are heated in alcoholuntil dissolution occurs. Then there is added 1 cc, of piperidine whileboiling the mixture and boiling is continued for about 1 hour. Aftercooling the dye separates in form of bluish red crystals. 7

The tetramethine dye is condensed with 2- methyl- [anthraceno-2'.1':4.5-thiazole] ethiodide in its alcoholic solution While boiling and inthe presence of diethyl amine to the unsymmetrical pentamethinecyanine.

The alcoholic solution of the dye has an absorption maximum at a Wavelength of about 6.95

Incorporated in a silver bromide emulsion containing about 4 per cent ofsilver iodide the dye impartsto it a range of sensitivity from about 650to 790 with a maximum at about 740 Example 12.'I'he dye[3-ethyl-5-diethylamino-benzthiazole- (2) [3-ethyl-{naphto-2'.1' :4.5-

thiazole}- (2) l-pentamethinecyanine perchlorate corresponding with theformula:

may be prepared by boiling 4 grams of 2-methyl--5-diethyl-aminobenzthiazole ethiodide with 3.5 grams of a-phenyl amidov-phenylimidopropene hydrochloride in 20 cc. of alcohol and adding 1.6grams of triethanolamine. The bluish red mixture is cooled and mixedwith 10 cc. of a 10 per cent solution of sodium perchlorate, whereby thetetramethine dye corresponding probably with the formula:

is precipitated in form of crystals. From alcohol the dye crystallizesin form of red-brown crystals.

The alcoholic solution of the compound has an absorption maximum at awave length of about 540,1L L.

1 gram of the intermediate product thus obtained is boiled with 0.6 gramof 2-methyl- [naphto-2'.1:4.5-thiazole diethylsulfate in 5 cc. ofalcohol and there are slowly added about 0.3 cc. of diethylamine,whereby the mixture assumes a blue-violet color. On the addition of afew cc. of a 10 per cent solution of sodium perchlorate the dye isprecipitated. The dye crystallizes from alcohol in form of brown-redsmall leaves.

The alcoholic solution of the dye has an absorption maximum at about 7051..

Incorporated in a silver bromide emulsion containing about 4 per cent ofsilver iodide the dye imparts to it a range of sensitivity from about650/.L/L to 810,1 1. with a maximum at about 750ml.

Example 13.The dye [3-ethyl-5-methoxybenzselenazole (2)[3-ethyl-l-phenyl-thiazole- (2)l-pentamethinecyanine iodidecorresponding with the formula:

C I C 2115 From the reaction mixture which assumes a deep red colorthere is precipitated the intermediate product corresponding probablywith the formula in' form' of red crystals. In order to complete theprecipitation of the intermediate product there are added 5 cc. of a 10per cent solution of potassium iodide. After filtering and washing withalcohol of 50 per cent strength the compound is recrystallized fromalcohol.

The alcoholic solution of the intermediate product has an absorptionmaximum at a wave length of about 540,11

The intermediate product thus obtained and 0.8 gram of2-methyl-4-phenylthiazole ethiodide are dissolved in 10 cc. of hotalcohol. The mixture is boiled while adding slowly 1 to 2 cc. ofdiethylamine until the mixture assumes a deep green color. After coolingthe dye separates in form of green crystals.

The alcoholic solution of the dye has an absorption maximum at about665/14L.

Incorporated in a silver bromide emulsion containing about 2 per cent ofsilver iodide the dye imparts to it a range of sensitivity from about570,114L to 790 with a maximum at about 700 l.

Example 14.For preparation of the dye [3- ethyl-5.6-diethoxybenzthiazole-(2)l [3-ethyl- 4-methyl thiazole (2) l pentamethinecyanineiodide corresponding with the formula:

(35115 I CQHIS 2 grams of 2-methyl-5.6-diethoxybenzthiazo1e ethiodidetogether with 2 grams of a-phenylamido-' -phenylimidopropenehydrochloride are dissolved while warming, in 10 cc. of alcohol and thenboiled for 2 hours with 1 cc. of an alcoholic solution of trimethylamineof 50 per cent strength. By adding about 20 cc. of a 5 per cent solutionof potassium iodide, the intermediate product corresponding probablywith the formula:

E C2115 I is separated from the dark-red reaction liquid as a dark-redtough oil which may be recrystallized from alcohol after washing withwater in the form of bluish red leaflets.

The alcoholic solution of the compound has an absorption maximum at awave length of about 535 1 gram of the intermediate product thusobtained is boiled with 1 gram of 2.4-dimethylthiazole ethiodide in 10cc. of alcohol, and, after the addition of about 2 cc. of diethylamine,heated for 10 minutes in a steam bath. While the unsymmetric dyeseparates the color of the mixture changes into a bluish-violet. Aftercooling, the precipitate is filtered off, washed with acetone andrecrystallized from alcohol in the form of green felted needles.

The alcoholic solution of the dye has an absorption maximum at about 675Incorporated in a silver bromide emulsion containing about 2 per cent ofsilver iodide the dye imparts to it a range of sensitivity from aboutGOO/LIL to 800 with a maximum at about 7 10 Examp e 15.In order toobtain [3-ethyl-5- methoxy benzselenazole (2)1 [1.6 dimethylrespondingwith the formula:

1 gram of the tetramethine dyestuff obtained according to Example 13 andcorresponding with the formula: 7

Incorporated in a silver bromide emulsion containing about 4 per cent ofsilver iodide the dye imparts to it a range of sensitivity from about650,L,L to 880 with a maximum at about 770/.L1L.

Example 16.[3-ethyl-6- ethoxy-benzthiazole- (2) -[3-ethyl-3'methyl-{naphto-1H2 24.5 thiazole}-(2) l-pentamethinecyanine iodidecorresponding with the formula:

CHa

is obtained according to Example 11 by condensing the intermediatedyestufi with 2.6-dimethyl-' 4.5-benzobenzthiazole ethiodide. Thedyestuff crystallizes from alcohol in the form of dark green leaflets.

The alcoholic solution of the dye has an absorption maximum at about685/LM.

Incorporated in a silver bromide emulsion containing about 2 per cent ofsilver iodide the dye imparts to it a range of sensitivity from about640 to 770 with a maximum at about 730 Ezmmple 17.-In order to obtainll-methylquinoline- (4)] [3.4 dimethyl thiazole (2) pentamethinecyanineiodide having the formula:

I OH:

. 2 grams of lepidine methiodide and 2 grams of a-phenyl-amidophenylimidopropene hydrochloride are dissolved in 10 cc. of alcohol andboiled for 2 hours after adding 1 cc. of diethyl-.

amine. ;After cooling, the crystallizes from alcohol. The alcoholicsolution s orption maximum 580mb; I

0.7 gram of the tetramethine dyestufi thus obintermediate product of thedye has an abat a wave length of about taine'd; probablycorrespondingwith the formula:

J l oH='oH--oH=oHN-o,m

. I H and 0.7 gram of 2.4-dimethylthiazole inetliiodidel are heated toboiling in 10 cc. of alcohol, while addingabout 1 cc. of diethylamine,until the mixtureassumes a violet-blue color. The dyestuif whichseparates on cooling is sucked on and Washed with acetone, f ntil theacetone runs out in a pure blue coloration. j f

,The dyestufi crystallizes from alcohol in the form of copper browncrystals. 5 Incorporated in a silver bromide emulsion containing about2% of silver iodide the dye im parts to it a range of sensitivity fromabout 650/141. to 830 with a maximum at about 790,1.

Example 18.-In order to prepare [l-ethylquinoline- (2)[3.4-dimethyl-5-carbethoxy-thiazole- (2)] pentamethinecyanine iodidecorresponding with the formula: V

. 2 l2 40-CH 8 llIfOH-OH oH oH on g c l ozHs I CH3 ,1 a mixture of 3grams of quinaldine ethiodide and 3 grams ofa-phenylamido-'y-phenylimidopropene hydrochloride is heated to weaklyboiling for a short period in 10 cc. of pyridine. By adding 10 cc. of a10 per cent solution of potassium iodide, the intermediate product isprecipitated from the deep red solution in the form of red floccules.The tetramethine dyestuif having probably the formula:

Qzfis \I c H crystallizes from alcohol in the form of violet red rods.-1 g l ;1 gram of the intermediate product and. 1 gram of2.4-dimethyl-5-carboethoxythiazole methiodide are boiled in 10 cc. ofalcohol, carefully mixed with about 1 cc. of diethylamine and keptboiling untilthe coloration changes to violet-blue. After cooling, thedyestuff separated, is sucked off,. washed with acetone andrecrystallized from alcohol. I The alcoholic solution of the dye has ansorption maximum at about 685,!L/L'.

Incorporated in a silver bromide emulsion containing about 2% of silveriodide the dye imparts to it a range of sensitivity from about 570/144to 82011., with a. maximum at about 730,LL,IL.

Example 19. In order to prepare [3-ethyl-6- ethoXy-benzthiazole-'(2)][3-ethyl{-t'etrahydronaphto 2'1 thiazole}-(2) l-pentamethinecyanineiodide corresponding with the formula:

1' g'ram'of l-ethyl-6-ethoxybenzthiazole tetramethinephenylamido iodide(intermediate product) obtained according to Example 11 and 1 gram of 2methyltetrahydro p3 naphthiazole ethiodide are heated to boiling for 5minutes in 10 cc. of alcohol While adding about 1 cc. of diethylamine.On cooling, the dye separates from the deep blue reaction liquid andforms light green crystals. 7

' It is purified by recrystallization from alcohol. The alcoholicsolution of the dye has an absorption maximum at about 670 Incorporatedin a silver bromide emulsion containing about 4% of silver iodide thedye im- 5 parts to it a range of sensitivity from about 610 to 78011-11.with a maximum at about 710w.

. Example 20.-For the preparation of [3-ethyl- 5'-ethoxy benzselenazole(2)] [3.4 dimethylthiazole-(2) l-pentamethinecyanine iodidecorresponding with the formula:

2 grams of 2-methyl-5-ethoxybenzselenazole mclo- CH=CHCH=CH-N-Cel15 HC2115 I separates. In order to complete the separation,

5 cc. of a 10 per cent solution of potassium iodide are added, theprecipitate is filtered off, washed with water and recrystallized fromalcohol.

The alcoholic solution of the dye has an absorption maximum at a wavelength of about 5351L/L.

1 gram ofthe intermediate product thus obtained and 1 gram of2.4-dimethylthiazole methiodide are boiled in 5 cc. of alcohol, whileadding about 2 cc. of an alcoholic solution of triethyl-' amine of 50per cent strength.

The dyestuff crystallizes from alcohol in the form of fine green feltedcrystals.

The alcoholic solution of the dye has an absorption maximum atabout655;.Lll.

Incorporated in a silver bromide emulsion containing about 2% of silveriodide the dye imparts to it a range of sensitivity from about 550 to7901141. with a maximum at about 690 Example 21.-In order to prepare[l-ethylquinoline (2) l-[3-ethyl 6-acetylaminobenzthiazole-(2)l-pentamethinecyanine iodide corresponding With theformula:

a mixture of 3 grams of quinoldine ethiodide and tion'oftriethanolamine. On cooling; the tetramethine dye probably correspondingwith the formula:

separates in the form of red violet crystals.

The alcoholic solution of the dye has an absorption maximum at a wavelengthof about 538lL/L.

For the condensation of [l-ethyl-quinoline- (2)l-[3-ethy1-6-acetylamino-benzthiazole-(2) l pentamethinecyanine iodide1.2 grams of the above intermediate product and 1 gram of 2-methyl-6-acetylaminobehzthiazole diethyl sulfate are boiled with about 1cc. of an alcoholic solution of triethanolamine until the dyestuficrystallizes out.

The alcoholic solution of the dye has an absorption maximum at about695/L1L.

Incorporated in a silver bromide emulsion containing about 4 per cent ofsilver iodide the dye imparts to it a range of sensitivity from about610 to 800 with a maximum at about 730 Example .22.In order to obtain[3- ethyl-5.6- dimethyl-benzthiazole- (2) l- [3-methyl-4-phenylthiazole(2)1-5 methyl pentamethinecyanine iodide having the formula:

2 grams of 2.5.G-trimethylbenzthiaZole ethicdide and 2 grams ofu-phenylamido- -phenylimido-p-methylpropene hydrochloride are heated toboiling after dissolution in 10 cc. of hot alcohol with 0.5 cc. of analcoholic solution of triethanolamine. dyestufi probably having theformula:

HaC-

H C2115 I separates as a brown-violet crystalline mass. The precipitateis filtered ofi, washed with cold alcohol and recrystallized fromalcohol for the purpose of purification.

The alcoholic solution of the dye has an absorption maximum at a Wavelength of about 53mm. f

In order to prepare the unsymmetrical dye, 0.8 gram of the intermediateproduct thus obtained and 1 gram of 2-methyl-4-phenylthiazole methiodideare boiled for 10 minutes, while adding about 2 cc. of an alcoholicsolution of diethylamine. The resulting dyestufi separates in greenishcrystals already during heating.

The alcoholic solution of the dye has an absorption maximum at about 665l.

'Incoroporated in a silver bromide emulsion containing about 2 per centoi silver iodide the dye imparts to it a' range of sensitivity fromabout 590/L/L to 7501 41. with a maximum at about 695 1 Example 23.Inorder to prepare [3-ethyl- 5.6- dimethylbenzthiazole- (2) l [lethyl-G-methyl- After cooling the intermediate sorption maximum' -ata-wav qen ui -1 gram of -tomqui Maine 'ethiodide ahd l" ram ofe-ph'e'nylamidb#516 mmethymenztmb-tgmeth yltetraniethine ethiodide asobtained" according to Example 2 2 are mixed with'aboutfl cc. of analcoholic solution Of diethylalnine While boiling m 15 cc. ofaleohol'and-"kept benin' untll -th' green coloration remains. Byaddin'e15 era: of 10 per cent} solution or "sodium perchlorate; theunsymmetrical {pen methi-ne'cyariine' isfprecipi tatedin blue floccules:Ablufsh black orys'talline powder crystallizesfrom al'olioli" Thealcoholic solution of the dyehasana'b sorption maximllm atabout{670;i;z." Incorporated in a; silver-bromide reunion (3on ta'iningabout l per cent ofsilver iodide the dye imparts to n arangeofsensititity fromflabout coo to soo l with aym'aximumat about 720 5ethoxy be'nzselenazole (zil tiafA-methyl thi azole- (2)'l+6methyl-pentamethinecyanine iodide corresponding-with theformula:

2 gram f Y 2 methyl-li ethokybenzselenoaiole ethiodide and 2 grams r: .1V G2I5\I t l about; cc: of' a 10f per cent *solution bf pm tassium-*i'odidefl are adde to' the red reaction liquid, thentne'mixtureisnuered and the rsi i due washed -with water;- "Gre'yish'redlafiets crystallize from alcohol The alcoholic solution of th-e dye'has' an' "abf' ven 1 gram or this tetrame'thineayeana 1 gram 7 of2.4-dimethylthia2oleinethiodide are -boild in 10"ccf ofalcohbL'lwhileadding 1 1202100. 0f diethylamine, until a; deep blueviolet 'colorationoccurs. Theidyes'tuff crystallizes from alcohol in the formof:'abluish"black='orystalline powder.

:Ea'ample 25.-In

{naphto 22124.5 thiazole}-'(2) ]-[3-- ethyl 4 inecyanine iodide having"theforrnula:

. ethiodide "and I 1 I gram of.

order to prepare- [3-ethyl-* 1 grani of- 2J4-'-dimethyl-5oarbethoxythiazole e-phenylamido-6.7- benzobenzthiazotetramethineRehiodide as obtainedaccording to Example 3: areheated in 15cc. ofalcohol while adding about 37cc. of an alcoholic solution oftrimethylamine of 50 per cent strength until the dyestuff separates inthe form of bronze crystals. I v t 1The: alcoholie solution' of the dyehas an absorptidn tin'axilmumrat about 675 at I i Incorporated" ih asilver bromide emulsion contaiiiing aboutnz per-.centtof': silver iodidethedye imparts" w it a range of sensitivity from about seen-to 'lflflm'with' a m'aximum at about 730 Ea:ample-.265 -In order to obtain[3-ethy1-5-: ethoxy-benzselenazole- (2) 1- [3,-ethy1-5-chloro-6-methylbenzthiazole (2),] pentamethinecyanine iodide as ebl'ai'nedv ac'ording to Example. and

1" gran1 of Z65dimethyl-5 chlorobenzthiazole ethiod'ide are boiledlinll'o 00,01" alcohol, then mixed witli 2.5 do. 'of asjolution ofsodium ethylate containing 3 per cent of sodium and heated until theresulting dye separates from the brownish green reaction liquid.'Ihe'dye crystallizes in the ,form of blackish-green 1 tablets fromalcoholi' The alcoholic solution of the dye has an absorption maximum atabout 675%. V lncorporated in a silver bromide emulsion con-- tainingabout 4 per cent of silver iodide the dye imparts to it a; range ofsensitivity from about 610m. to;780;mewithlagmaximumat about 720 Example27.In order to prepare [3-ethyl-6- methyLr-I benzthiazole- (2).1 -3-ethyl {acenaph- -theno 5 A; 4.5;; thia zole} 2):]pentamethinecyanine'iodide corresponding with theformula: I

the

2 erating- 6r 2 megmI-ptbmunmime ethiodide and 2 grarns "ofuphenylalmido-7-phenylimidopropenehydrochloride are dissolved in about 1Occ; bf hdt'aloohol and'heated to'boiling for about t 2 hours afteradding 0.6 gram of piperidine. The intermediateproduct which separateson cooling and probably corresponds with the formula:

isiecrystallizedf rom alcohol in order to free it from symmetricalpentamethinecyanine formed simultaneously. o

e alcoholic solution of thedyestuff has an absorption maximum at 'a wavelength of about 515m l l c In order to produce[3-ethyl-6-methyl-benzthiazole-(2) l-3-ethyl {acenaphtheno 5'.4 :45-thiazole}-(2)]-lpentamethinecyanine iodide, 0.5 gram of the tetramethinedyestufi and 0.5 gram of 2-methylacenaphthenethiazole ethiodide areboiled in 10 cc. of alcohol together with 0.5 cc. of piperidine. Theunsymmetrical dyestufi which separates out in the form of green crystalscrystallizes from alcohol in the form of hairfine green needles.

The alcoholic solution of the dye has an absorption maximum at about675(1-[LL Incorporated in a'silver bromide emulsion containing about 4per cent of silver iodide the dye imparts to it a range of sensitivityfrom about 600 l to 790 with amaximum at about 715.

Example 28.-'-For the preparation of. [Ev-ethyl-5.fi-dimethyl-benzthiazole- (2) l- [3-ethyl-5-chlo ro-benzselenazole-(2) l-pentamethinecyanine iodide corresponding with the formula:

l 6 a 2 o11=on-o121:011-011- a 5 01 f 4 C Hs I 0211:

a mixture of 4 grams of 5.6-trimethylbenzthiazole ethiodide and 5 gramsof a-phenylamido- -phenylimidopropene hydrochloride are heated toboiling with 1 cc. of piperidine for about '2 hours in 20 cc. ofalcohol; The int'ermediateproduct which separates on cooling-andprobably has the formula:

1130'- LCH=OHCH=CH-NOHi" can I is recrystallized from alcohol and forms'carmine red little rods.

.The alcoholic solution ofthe dye has .anabsorption ;maximum at a .wavelength of-about 525mb.

In order to obtain -1.1'-diethyl 5.6-dimethyl-- benzthio 6-chlorobenzselenopentacarbocyanine iodide 1 gram of the tetramethine dyeand 1 gram of 2-methyl-5-chlorobenzselenoazole are heated to boiling forabout 10 minutes in 15 cc. of pyridine. On adding 15 cc. of a 5 per centsolution of potassium iodide the .dyestuff separates. From alcohol thedyestuff crystallizes in the form of fine green needles. V

The alcoholic solution of the dye has an absorptionmaximum at about 665Incorporated in a silver bromideemulsion; con: taining about 4 per centof silver iodide the dye imparts to it .a range of GOO/LIL to 770 with amaximum at about 705 What I claim is:

l. The process of producing an unsymmetrical methinecyanine whichcomprises reacting on the quaternary ammonium salt of a nitrogenousheterocyclic base selected from the group consisting ofa-methylthiazoles, wmethylselenazoles, oc-II'lCthYlCllllllOllXlGS andv-methylquinolines with an u-phenylamido-' -phenylimidopropenehydrohalide in the presence of an amount of alkaline condensing agentnot greaterthan the quantity equivalent to that of the base, andcondensing the resulting intermediate product with-another quaternaryammonium salt of .a nitrogenous base selected from the group consistingof -methylthiazoles, a-methylselenazoles, oc-IIIEthYlQlliIlO-sensitivity from about lines, and methylquinolines in the presence of analkaline condensing agent.

2. The process of producing an unsymmetrical methinecyanine whichcomprises reacting on the quaternary ammonium salt of a nitrogeneousheterocyclic base selected from the group consisting ofa-methylthiazoles, a-methylselenazoles, ozmethylquinolines, and'y-methylquinolines with an amount of an u-phenylamido-'-phenylimidopropene hydrohalide substantially surpassing the quantityequivalent to that of the base in the presence of an amountof alkalinecondensing agent not greater than the quantity equivalent to that of thebase, and condensing the resulting intermediate product with anotherquaternary ammonium salt of a nitrogenous base selected from the groupconsisting of a-methylthiazoles, -methylselenazoles, a-methylquinolines,and methylquinolines in-the presence of an alkaline condensing agent.

3. The process of producing an unsymmetrical methincyanine whichcomprises reacting on the quaternary ammonium salt of a nitrogenousheterocyclic base selected from the group consisting ofa-methylthiazoles, a-methylselenazoles, amethylquinolines, and-methylquinolines with an amount of an a-phenylamidowephenylimidopropenehydrohalide substantially surpassing the quantity equivalent to that ofthe base in the presence of an amount of an amine not greater than thequantity equivalent to that of the base, and. condensing the resultingintermediate product with another quaternary ammonium salt of anitrogenous base selected from the group consisting ofa-methylthiazoles, a-methylselenazoles, a-methylquinolines and'y-methylquinolines in the presence of an amine.

4. The process of producing [3-ethyl-benzselenazole- (2)[3-ethy1-4-methyl-thiazole- (2) lpentamethinecyanine iodide, whichcomprises reactingon Z-methylbenzselenazole ethiodide witha-phenylamido-'y-phenylimidopropene hydrochloride in the presence of anamount of triethanolamine not greater than the quantity equivalent tothat of said heterocyclic base, and condensing the resultingintermediate product with 2.4-dimethylthiazole ethiodide in the presenceof sodium ethylate.

..-5. Theprocess of producing [1-methyl-quinoline- (4) l- [3 ethyl-benzthiazole- (2) l pentamethinecyanine iodide, which comprisesreacting on lepidine methiodide with a-phenylamido-v-phenylimidopropenehydrochloride in the presence of an amount of triethanolamine notgreater than the quantity equivalent to that of said heterocyclic base,and condensing the resulting intermediate product withZ-methylbenzthiazole ethiodide in the presence of diethylamine.

. 6. The process of producing [3-ethyl-5.6-dimethylbenzthiazole- (2) l[I-ethyI-G-methylquinoline (2) l 6 methylpentamethinecyanineperchlorate, which comprises reacting on 2.5.6-trimethylbenzthiazoleethiodide with aphenylamino- -phenylimido ,3 methylpropene hydrochloridein the presence of an amount of triethanolamine not greater than thequantity equivalent to that of said heterocyclic base, and condensingthe resulting intermediate product with ptoluquinaldine ethiodide in thepresence of diethylamine.

WALTER ZEH.

